Refrigeration – Gas compression – heat regeneration and expansion – e.g.,...
Reexamination Certificate
1999-07-23
2001-04-03
Capossela, Ronald (Department: 3744)
Refrigeration
Gas compression, heat regeneration and expansion, e.g.,...
C060S517000, C310S013000, C417S488000
Reexamination Certificate
active
06209328
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pulse tube refrigerator driven by an oil free type compressor, and in particular to a compressor integrated pulse tube refrigerator of an oil free type which is capable of maintaining an accurate gap between an inner surface of a cylinder and an outer surface of a piston so that a gas is not leaked through the gap to the outside in a state that the piston does not contact with an inner surface of the cylinder when the piston reciprocates within the cylinder.
2. Description of the Background Art
Generally, as a ultra low temperature refrigerator which is used for cooling a small size electronic component and a super-conductive material, a thermal reproducing type refrigerator such as a Stirling refrigerator, a GM refrigerator, etc. is used.
The resistance of most typical electronic components are decreased at a low temperature for thereby increasing an operational efficiency of the components, and the processing speed of a CPU(Central Processing Unit) used for a computer is increased.
In addition, as the super-conductive product is intensively studied, the need for a low temperature price ultra low refrigerator which is capable of satisfying the cooling conditions of the small size components is gradually increased.
In order to increase the reliability of the above-described refrigerator, the operation speed is decreased, or a lubricating operation is enhanced for preventing an abrasion between the friction portions during a pumping operation of a working gas, or the characteristic of a sealant is improved. In addition, the number of the operational portions is decreased.
Recently, as a ultra low temperature refrigerator which has a high reliable operation and is capable of implementing a high speed operation and does not need an additional lubricating operation and a maintenance for a long time, an oil free type compressor pulse tube refrigerator is disclosed.
The above-described oil free type compressor pulse tube refrigerator is directed to implementing a ultra low temperature refrigerating operation at an open side of the tube using a principle that when varying a pressure by periodically injecting a gas having a certain temperature into a one side-blocked tube, a large temperature variation is obtained at a portion in which there is a turbulent flow of the gas. Namely, the oil free type compressor pulse tube refrigerator is a refrigerator having a low average pressure and pressure ratio and a low refrigerating capacity. In the oil free type compressor pulse tube refrigerator, the pulse tube refrigerator includes one movement unit of a compressor compared to the conventional Stirling refrigerator having two movement units of a piston and displacer.
As a pulse tube refrigerator, there are a basic type pulse tube refrigerator, a resonance type pulse tube refrigerator having an acoustic driving unit, a hole type pulse tube refrigerator fabricated by installing an orifice, which generates a phase difference of a pressure pulse and a mas flow rate, and a storing container at the basic type pulse tube refrigerator, and an inertia tube type pulse tube refrigerator using an inertance tube(long neck tube) instead of the orifice. Among the above-described refrigerators, the basic type pulse tube refrigerator, the hole type pulse tube refrigerator and the inertia tube type pulse tube refrigerator will be explained.
First, as shown in
FIG. 1
, the basic type pulse tube refrigerator includes a driving unit M, a hollow pulse tube
1
having a warm end
1
a
and a cold end
1
b
for introducing a working gas pumped by the driving unit M for thereby compressing and expanding the gas therein, and a reproducing unit
2
connected between the driving unit M and the pulse tube
1
for maintaining a certain temperature of the working gas which contains a sensible heat due to a temperature difference based on the compressing and expanding operations of the working gas.
In the drawing, reference numerals
2
a
and
2
b
represent the connection tubes.
The operation of the basic type pulse tube refrigerator will be explained with reference to the accompanying drawings.
First, when the driving unit M pushes the working gas into the interior of the reproducing unit
2
, the thusly pushed high temperature and pressure working gas having a sensible heat flows through the reproducing unit
2
and is flown into the pulse tube
1
. The working gas in the pulse tube
1
is flown toward the blocked side and then is more compressed. At the warm end portion
1
a, a heat is radiated based on a heat transfer operation at the tube wall.
On the contrary, when the driving unit M sucks the working gas, the gas introduced into the interior of the pulse tube
1
is discharged, and the working gas in the pulse tube
1
is expanded, the heat is absorbed at the cold end
1
b
by a heat transfer at the tube wall. The above-described operation is repeatedly performed, so that it is possible to obtain a ultra low temperature(about −20° C.) at the cold end. At this time, the working gas discharged from the pulse tube
1
absorbs the heat stored in the reproducing unit
2
and is heated by a certain temperature and is introduced into the driving unit M.
The hole type pulse tube refrigerator will be explained with reference to the accompanying drawing.
First, as shown in
FIG. 2
, the hole type pulse refrigerator includes a driving unit M, a pulse tube
3
having a warm end portion
3
a
at which a gas is compressed and a cold end
3
b
at which a gas is expanded, as the working gas pumped by the driving unit M is inwardly introduced for thereby implementing a certain mass flow rate of the working gas, an orifice
4
connected with the warm end portion
3
a
of the pulse tube
3
for generating a certain phase difference based on the mass flow rate of the flowing working gas and the pressure pulse operation, a storing container
5
connected with the orifice
4
and holding the working gas therein for a certain time, and a reproducing unit
6
connected between the cold end
3
b
and the driving unit M for storing a sensible heat of the working gas pumped toward the pulse tube
3
and supplying the stored heat when the working gas flows from the pulse tube
3
to the driving unit M.
In the drawing, reference numerals
4
a
,
6
a
and
6
b
represent the connection tube.
The operation of the hole type pulse tube refrigerator is similar with the basic type pulse tube refrigerator except for the following difference. Namely, in the basic type pulse tube refrigerator, the heat is radiated from the working gas via the tube wall of the pulse tube
1
. In the hole type pulse tube refrigerator, the working gas flows through the orifice
4
and increases the phase difference between the mass flow rate and the pressure pulse operation based on an adiabatic expansion for thereby obtaining a higher cooling capability.
Namely, in the hole type pulse tube refrigerator, when the working gas is supplied by the driving unit M and flows via the reproducing unit
6
and is introduced into the pulse tube
3
, the working gas filled in the pulse tube
3
is adiabatically compressed, so that the temperature of the working gas is increased and is penetrated into the orifice
4
, whereby the working gas is expanded by the orifice
4
and is filled in the storing container
5
.
In addition, in the basic pulse tube refrigerator, the working gas is re-heated by receiving the heat from the tube wall, and in the hole type pulse refrigerator, the working gas is heated while the working gas flows the orifice
4
and is adiabatically compressed in the pulse tube
3
.
When the working gas is sucked by the driving unit M, the working gas is adiabatically expanded due to a mass flow rate difference between the working gas flown from the pulse tube
3
and the working gas introduced into the pulse tube
3
via the orifice
4
when the working gas is flown from the pulse tube
3
to the reproducing unit
6
, so that the temperature of the working gas is decreased.
Hong Kee Yong
Kim Seon Young
Kim Sung Tae
Birch & Stewart Kolasch & Birch, LLP
Capossela Ronald
LG Electronics Inc.
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